Key Technical Field:
This involves the field of electronic products, particularly the design and manufacturing technology of rigid-flex circuit boards.
Overview of Background Technology:
With the continuous development of consumer electronic products, the requirements for circuit boards are becoming increasingly high, including aspects such aslightweight, easy assembly, signal transmission speed, and product reliability. The rigid-flex design is gaining more attention due to its unique advantages. Traditional manufacturing methods for rigid-flex boards, such as removing the cover layer in the window area to expose internal circuits, have some issues, such asthe processes of punching, bonding, and baking increasing production costs and raising the risk of damage to the polyimide (PI) material in the metallization process, which may lead tocopper foil damage.
Objective of the Invention:
To address the issues in the manufacturing process of rigid-flex circuit boards in the prior art, this invention aims to provide a new rigid-flex circuit board and its manufacturing method, with the goal ofreducing production costs, improving efficiency, and minimizing the risk of copper foil damage.
Main Invention Content/Core Idea:
This invention provides a method for manufacturing rigid-flex circuit boards, which effectively removes the protective layer in the window area through shadow processing after pre-window treatment, while retaining the protective layer in the non-window area as a seed layer, thereby improving the adhesion of the copper layer on the second substrate. Compared to the traditional method of applying a cover film to the window area and then removing it, this methodsaves processes and improves efficiency.
Key Steps (Summarized from Abstract and Specific Implementation):
- Providing the first circuit board and first substrate: The first circuit board includes a first substrate and a first conductive circuit layer and a second conductive circuit layer formed on two opposite surfaces of the first substrate and electrically connected. The first substrate includes a flexible second substrate laminated on the surface of the first adhesive layer, a protective layer formed on the surface of the second substrate, and a first copper layer formed on the surface of the protective layer.
- Laminating the first circuit board and first substrate: The first substrate is laminated onto the surface of the first circuit board using two first adhesive layers.
- Drilling process: Holes are drilled in the laminated first circuit board and first substrate to form through holes.
- Electroplating, etching, and other processes: The first circuit board and first substrate undergo electroplating, etching, film pressing, exposure, and film removal processes to form a third conductive circuit layer and a fourth conductive circuit layer.
- Removing the protective layer using dry film: The protective layer exposed on the third and fourth conductive circuit layers is partially covered using dry film or other methods, and the uncovered area of the protective layer is removed.
- Forming the second copper layer: A second copper layer and two second adhesive layers are provided, and the second copper layer is laminated onto the surface of the rigid-flex circuit board semi-finished product using the two second adhesive layers. Pre-window treatment forms the window area.
- Drilling process: The semi-finished rigid-flex circuit board undergoes a drilling process to create a second accommodating hole in the second copper layer.
- Conducting shadow processing: The protective layer in the window area is removed. The protective layer in the window area will be removed after lamination, thus structurally having the characteristic that the edge of the window area has a protective layer.
- Electroplating, etching, and other processes: The semi-finished rigid-flex circuit board undergoes electroplating, etching, film pressing, exposure, film removal, and solder mask printing processes to form a fifth conductive circuit layer and a sixth conductive circuit layer, covered with a solder mask or cover film (such as CVL).
Key Materials:
- First substrate: Options include polyimide (PI), liquid crystal polymer (LCP), polyether ether ketone (PEEK), polyethylene terephthalate (PET), and polyethylene naphthalate (PEN), among others.
- Second substrate: Same material options as above.
- Protective layer: Options include one of Ni, Cr, Ti, Cu, Ag, Al, Zn, Sn, Fe, or any other material that can reduce the formation of protective layer substances under light exposure.
- First adhesive layer: A sticky resin, options include at least one of polypropylene, epoxy resin, polyurethane, phenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin, and polyimide.
- Second adhesive layer: Same material options as above.
Advantages/Effects:
- Through shadow processing, the protective layer in the window area is effectively removed, while retaining the protective layer in the non-window area as a seed layer, improving the adhesion of the copper layer on the second substrate.
- It resolves the copper foil damage and other adverse conditions that occur in the metallization treatment of the protective layer in traditional methods.
- Compared to the traditional method of applying a cover film to the window area and then removing it, this method saves processes and improves efficiency.
Illustration Description:
Shows cross-sectional views of different stages in the manufacturing process of rigid-flex circuit boards.
Claims:
The claims section details the specific steps and features of the claimed rigid-flex circuit board and its manufacturing method, covering key process steps such as material selection, lamination structure, drilling, electroplating, etching, and protective layer removal. It particularly emphasizes the removal of the protective layer in the window area through shadow processing and the selection of protective layer materials.
Summary:
This invention provides an improved method for manufacturing rigid-flex circuit boards, focusing on optimizing the processing of the protective layer in the window area. By effectively solving the issues of incomplete removal of the protective layer and copper foil damage in traditional methods through shadow processing technology, it enhances product reliability, production efficiency, and reduces costs. This technology is of significant importance for promoting the further application of rigid-flex circuit boards in fields such as consumer electronics.
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